As image forming methods utilized for patterning and the like of electronic components such as semiconductor integrated circuits, liquid crystal display devices and printed wiring boards, there are known methods of utilizing positive-type photoresists using as a raw material a positive-type photosensitive resin composition containing a novolac-type phenol resin and 1,2-quinonediazide compound (for example, Patent Literatures 1 to 6).
In the case where a photosensitive layer is formed by applying a positive-type photosensitive resin composition on a substrate or the like, it is usual that the film thickness of the layer is 0.5 to several microns. When such a positive-type photosensitive resin composition is used, the formation of an image pattern over wide dimensional ranges is enabled. The dimensional range has wide ranges of, for example, from a sub-half-micron region of about 0.3 μm to a considerably large dimensional width of about several hundred microns. Thereby, the microfabrication of a wide variety of substrate surfaces is enabled.